Ligand selection for ternary oxide thin films

ABSTRACT

Embodiments of the present invention are directed to forming a ternary compound using a modified atomic layer deposition (ALD) process. In a non-limiting embodiment of the invention, a first precursor and a second precursor are selected. The first precursor includes a first metal and a first ligand. The second precursor includes a second metal and a second ligand. The second ligand is selected based on the first ligand to target a second metal uptake. A substrate is exposed to the first precursor during a first pulse of an ALD cycle and the substrate is exposed to the second precursor during a second pulse of the ALD cycle, the second pulse occurring after the first pulse. The substrate is exposed to a third precursor (e.g., an oxidant) during a third pulse of the ALD cycle. The ternary compound can include a ternary oxide film.

BACKGROUND

The present invention generally relates to film deposition techniques.More specifically, the present invention relates to the selection ofligands when depositing ternary oxide (mixed metal-oxide) thin films.

The semiconductor industry is characterized by a trend towardfabricating larger and more complex circuits on a given semiconductorchip. The larger and more complex circuits are achieved by reducing thesize of individual devices within the circuits and spacing the devicescloser together. In recent years, high dielectric constant (high-k)materials have gradually replaced silicon dioxide as the insulatinglayer used in state-of-the-art CMOS fabrication technologies, including,for example, the CMOS fabrication technologies used to fabricate memorycells in a semiconductor memory device. Zirconium oxide (ZrO), forexample, has a dielectric constant from about 24 to 40. To meet thescaling requirements for smaller and smaller devices, these high-k filmsmust be deposited to increasingly lower thickness levels.

Atomic layer deposition (ALD) is a deposition technique uniquely suitedfor thin-film deposition. During ALD a film is grown on a substratelayer by layer by exposing the substrate surface to alternating gaseousspecies, typically referred to as precursors. The precursors aredeposited during a series of sequential, non-overlapping pulses. In eachof these pulses the precursor molecules react with the surface in aself-limiting way so that the reaction terminates once all the reactivesites on the surface are consumed. Consequently, the maximum amount ofmaterial deposited on the surface after a single exposure to all of theprecursors (a so-called ALD cycle) is determined by the nature of theprecursor-surface interaction. By varying the number of cycles, it ispossible to grow materials uniformly and with high precision onarbitrarily complex and large substrates.

SUMMARY

Embodiments of the invention are directed to a method for forming acompound (e.g., a ternary oxide film) using a modified atomic layerdeposition (ALD) process. A non-limiting example of the method includesselecting a first precursor and a second precursor. The first precursorcan include a first metal and a first ligand. The second precursor caninclude a second metal and a second ligand. The second ligand isselected based on the first ligand to target a second metal uptake. Asubstrate can be exposed to the first precursor during a first pulse ofan ALD cycle. The substrate can be exposed to the second precursorduring a second pulse of the ALD cycle. The second pulse can occurdirectly after the first pulse without an intervening oxidant pulse. Thesubstrate can be exposed to a third precursor during a third pulse ofthe ALD cycle. In some embodiments of the invention, the third precursoris an oxidant.

In some embodiments of the invention, the metal of the first precursorchemisorbs onto a surface of the substrate during the first pulse. Insome embodiments of the invention, one or more adsorption sites remainopen after the first pulse. In some embodiments of the invention, themetal of the second precursor chemisorbs onto the one or more openadsorption sites during the second pulse.

In some embodiments of the invention, the first ligand and the secondligand react during the second pulse to form one or more byproducts. Insome embodiments of the invention, at least a portion of the one or morebyproducts are removing using off-gassing.

In some embodiments of the invention, the second pulse occurs directlyafter the first pulse without an intervening pulse. In some embodimentsof the invention, the second pulse occurs after the first pulse suchthat any intervening pulse is a non-reactive purge pulse. In someembodiments of the invention, a precursor partial pressure, gas flow,and pulse time are selected for at least one of the first pulse and thesecond pulse based on the target second metal uptake.

Embodiments of the invention are directed to a method for depositing aternary oxide film. A non-limiting example of the method includesselecting a first metal and a second metal for the ternary oxide. Atarget second metal uptake (final second metal concentration in thefilm) is also selected for the ternary oxide. The method includesdetermining, based on the first metal and the second metal, one or moreligand pairs with known second metal uptakes. The method includesselecting, based on the target second metal uptake and the known secondmetal uptakes, a first ligand pair of the one or more ligand pairs. Thefirst ligand pair includes a first ligand and a second ligand. Themethod includes exposing a substrate to an ALD cycle having a firstprecursor pulse, a second precursor pulse, and an oxidant pulse. Thefirst precursor includes the first metal and the first ligand, and thesecond precursor includes the second metal and the second ligand.

In some embodiments of the invention, the method includes selecting,based on the target second metal uptake and the known second metaluptakes, a second ligand pair of the one or more ligand pairs. Thesecond ligand pair includes a third ligand and a fourth ligand.

In some embodiments of the invention, the ALD cycle is a first ALD cycleand a first portion of the ternary oxide is formed using the first ALDcycle. In some embodiments of the invention, a second portion of theternary oxide is formed using a second ALD cycle. In some embodiments ofthe invention, the second ALD cycle includes a third precursor pulse, afourth precursor pulse, and an oxidant pulse. The third precursorincludes the first metal and the third ligand and the fourth precursorincludes the second metal and the fourth ligand.

In some embodiments of the invention, the ALD cycle is repeated one ormore times.

In some embodiments of the invention, the first ligand is selected froma first class of ligands and the second ligand is selected from a secondclass of ligands different than the first class.

In some embodiments of the invention, the ternary oxide includes aferroelectric phase or an anti-ferroelectric phase.

Embodiments of the invention are directed to a method for forming anelectronic device. A non-limiting example of the method includes forminga bottom layer and forming a top electrode over the bottom layer. Themethod includes forming a ternary oxide film between the bottom layerand the top electrode. The ternary oxide film can be formed by exposingthe bottom layer to an ALD cycle having a first precursor pulse, asecond precursor pulse, and an oxidant pulse. The first precursor caninclude a first metal and a first ligand, and the second precursor caninclude a second metal and a second ligand. The second ligand can beselected based on the first ligand to target a second metal uptake.

In some embodiments of the invention, the ternary oxide film includes anactive area of a resistive random-access memory (RRAM) or a gatedielectric layer of a floating gate flash memory.

In some embodiments of the invention, the ternary oxide film includes athickness of less than about 2 nm and a second metal concentration ofless than 15 percent. In some embodiments of the invention, the secondmetal is distributed throughout the ternary oxide film.

Embodiments of the invention are directed to a semiconductor structure.A non-limiting example of the semiconductor device includes a bottomlayer, a top electrode, and a ternary oxide film between the bottomlayer and the top electrode. The ternary oxide film can be formed byexposing the bottom layer to an ALD cycle having a first precursorpulse, a second precursor pulse, and an oxidant pulse. The firstprecursor can include a metal and a first ligand and the secondprecursor can include a second metal and a second ligand. The ternaryoxide film can include a thickness of less than about 2 nm and a secondmetal concentration of less than 15 percent. The second metal can bedistributed throughout the ternary oxide film.

In some embodiments of the invention, the second metal concentration isless than 6 percent, or less than 3 percent.

In some embodiments of the invention, the ternary oxide film includes agate dielectric layer of a floating gate flash memory.

In some embodiments of the invention, the semiconductor materialincludes one or more of Si, Ge, SiGe, aSi:H, and InGaAs.

Embodiments of the invention are directed to a metal-insulator-metaldevice. A non-limiting example of the device includes a bottom electrodehaving a first metal, a top electrode having a second metal, and aternary oxide film between the bottom electrode and the top electrode.The ternary oxide film can be formed by exposing the bottom layer to anALD cycle having a first precursor pulse, a second precursor pulse, andan oxidant pulse. The first precursor can include a metal and a firstligand and the second precursor can include a second metal and a secondligand. The ternary oxide film can include a thickness of less thanabout 2 nm and a second metal concentration of less than 15 percent. Thesecond metal can be distributed throughout the ternary oxide film.

In some embodiments of the invention, the bottom electrode includes ametal-nitride and the ternary oxide film includes HfO_(2-x) orTa₂O_(3-x).

In some embodiments of the invention, the ternary oxide film includesone or more metal-metal bonds and one or more metal-nitride-metal bonds.

Additional technical features and benefits are realized through thetechniques of the present invention. Embodiments and aspects of theinvention are described in detail herein and are considered a part ofthe claimed subject matter. For a better understanding, refer to thedetailed description and to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The specifics of the exclusive rights described herein are particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features and advantages ofthe embodiments of the invention are apparent from the followingdetailed description taken in conjunction with the accompanying drawingsin which:

FIG. 1 depicts the growth of a ternary oxide using atomic layerdeposition;

FIG. 2 depicts the selection of ligand combinations to target a specificsecond metal uptake in accordance with embodiments of the invention;

FIG. 3 depicts a cross-sectional view illustrating a structure thatresults from performing initial fabrication operations in accordancewith embodiments of the invention;

FIG. 4 depicts a cross-sectional view of the structure after fabricationoperations in accordance with embodiments of the invention;

FIG. 5 depicts a cross-sectional view of the structure after fabricationoperations in accordance with embodiments of the invention;

FIG. 6 depicts a cross-sectional view of the structure after fabricationoperations in accordance with embodiments of the invention;

FIG. 7A depicts a top-down view of a structure after fabricationoperations in accordance with embodiments of the invention;

FIG. 7B depicts a cross-sectional view of the structure of FIG. 7A afterfabrication operations in accordance with embodiments of the invention;

FIG. 8 depicts a flow diagram illustrating a method according to one ormore embodiments of the invention;

FIG. 9 depicts a flow diagram illustrating a method according to one ormore embodiments of the invention; and

FIG. 10 depicts a flow diagram illustrating a method according to one ormore embodiments of the invention.

In the accompanying figures and following detailed description of thedescribed embodiments, the various elements illustrated in the figuresare provided with two or three digit reference numbers. With minorexceptions, the leftmost digit(s) of each reference number correspond tothe figure in which its element is first illustrated.

DETAILED DESCRIPTION

For the sake of brevity, conventional techniques related tosemiconductor device and integrated circuit (IC) fabrication may or maynot be described in detail herein. Moreover, the various tasks andprocess steps described herein can be incorporated into a morecomprehensive procedure or process having additional steps orfunctionality not described in detail herein. In particular, varioussteps in the manufacture of semiconductor devices andsemiconductor-based ICs are well known and so, in the interest ofbrevity, many conventional steps will only be mentioned briefly hereinor will be omitted entirely without providing the well-known processdetails.

Turning now to an overview of technologies that are more specificallyrelevant to aspects of the invention, current atomic layer deposition(ALD) techniques for depositing ternary oxides (e.g., M1M2O, with M1being a first metal, M2 a second metal, and O an oxidant) combineseveral sequential M1L1-O1 and M2L2-O2 ALD cycles. Most conventional ALDsupercyles also include an intervening oxidant pulse between the metalpulses. In this scheme, O1 oxidizes M1, removes some or all of theremaining L1 ligands, and can generate new ligands such as —OH that arereactive towards M2L2. In each cycle, a substrate is exposed to eitherthe M1 or M2 precursor. The final ternary oxide stack is slowly built upby stacking the resulting M1 and M2 layers. While suitable fordepositing ternary oxides having relatively equal M1 and M2 targetconcentrations, this implies that for a low target M2 content, a lowcycle ratio has to be used (for precursors with similar number densityat saturation), resulting in long, thick supercycles.

FIG. 1 illustrates growing a ternary oxide (HfZrO) with a low ˜3 cation% Zr target using conventional ALD. In this case, supercycles of[16*(M1L1-O1)]-M2L2-O2-[16*(M1L1-O1)] have to be used, depositing about2.0 nm per supercycle. In this example, M1L1 is TEMAH(tetrakis-ethylmethylamino (TEMA) and hafnium), M2L2 is TEMAZr, O1 isH2O, and O2 is oxygen. As shown in FIG. 1, achieving 3% Zr via ALDrequires 32 HfO cycles and a single Zr cycle. The Zr cycle is typicallyplaced between equal numbers of the HfO cycles. In this case, the Zrcycle occurs between two groups of 16 HfO cycles. Each cycle results ina growth or deposition of about 0.06 nm of material. Consequently, thefinal stack includes 32 HfO cycles having a total thickness of 1.92 nmand a single ZrO cycle having a total thickness of 0.06 nm, providingabout 3.03% Zr.

There are several limitations inherent to the conventional ALD process.As shown in FIG. 1, the deposited film is a nanolaminate with highlynon-uniform M2 depth distribution. This is a direct result of the layerby layer (cycle by cycle) deposition. Moreover, for thin films (e.g.less than 5 nm), a low number of relatively thick supercycles results inpoor M2 cation % controllability, and ultimately, in an inability toachieve the desired low M2 cation %. In effect, there is a minimum floorto the M2 concentration that can be achieved for a given film stackthickness, because at least a single M2 layer is required usingconventional ALD.

Turning now to an overview of the aspects of the invention, embodimentsof the invention provide a new ALD technique for depositing thin-filmternary oxides. In this process the M2 pulses occur right after the M1pulses, without intervening oxidant (or other reactant) pulses. Thechemisorbed M1 and its remaining ligands block some or all of theadsorption/reaction sites, reducing the M2 uptake during the subsequentM2L2 pulse. The M2 uptake is further tuned by carefully selectingdifferent precursor ligands having different relative sizes to modifyhow much of the substrate surface will be exposed to the secondprecursor (or viewed alternatively, how much of the substrate surface isblocked by the first precursor ligands).

Consider the deposition of ALD metal precursors P1 and P2, where P1includes a first metal and a first ligand (e.g., M1La) and P2 includes asecond metal and a second ligand (e.g., M2Lb). In some embodiments ofthe invention, the M2Lb pulses occur right after M1La pulses, without anintervening oxidant (or other reactant) pulse. In some embodiments ofthe invention, the first ligand La and the second ligand Lb are selectedsuch that the first ligand La is relatively small and the second ligandLb is relatively large. For example, the first ligand La can be arelatively small chloride (e.g., Cl₄ or Cl₃) and the second ligand Lbcan be a relatively large metalorganic molecule (e.g., a trimethylmetalorganic or a tetramethylethyl metalorganic, such as Al₂(CH₃)₆). Insome embodiments of the invention, ligands having specific differencesin relative size are selected to achieve a targeted M2 uptake.

As shown in FIG. 2, selecting the ligands in this manner can reduce M2uptake by 80% or more (80%, 85%, 90%, 95%, 99%, or even completely),without changing the number of supercyles. For example, a TEMAZr pulsefollowed by an HfCl4 pulse for 80 cycles (split 5) provides an Hfconcentration of about 48.6 percent, while a TEMAZr pulse followed by aTEMAHf pulse for 80 cycles (split 7) provides an Hf concentration ofabout 27.2 percent. Notably, this wide range of Hf concentrations (M2uptake) were achieved without varying the number of cycles.

Benefits of this technique over prior ALD processes include the abilityto form conformal and uniform thin-film ternary oxides having a moreuniform M2 depth distribution. Moreover, decoupling the M2 cation % fromthe number of needed supercycles improves M2 cation % controllabilityand allows for lower M2 concentrations, even for very thin (sub 5 nm)films.

ALD techniques in accordance with aspects of the invention have a widerange of practical applications, such as in metal-insulator-metal (MIM)stacks, 3D memory oxides, 3D flash devices, resistive random accessmemory (RRAM), or in high-k dielectric films, such as those used in FETsand MIMCAPs. For example, ALD processes in accordance with aspects ofthe invention can be used to build M:HfO₂ or M:ZrO₂ high-k dielectricfilms having arbitrarily low cation % M (e.g., 3-15% or even sub 3%)even for very thin film thicknesses of 0.5 to 10 nm. These films can beused to build DRAM, MIMCAP, FET, or RRAM devices, among otherapplications. In another example, ALD processes in accordance withaspects of the invention can be used to form thin Al-doped ZrO₂ films(e.g., for DRAMs). These ALD processes can also be used to formferroelectric or anti-ferroelectric films. For example, M:HfO₂ or M:ZrO₂films with 2-6 cation % M (M can include any suitable metal orsemiconductor material, such as Si, Al, Mg, La, Gd, Sr, etc.) can beincorporated in a broad range of devices, such as FeFET, FeRAM, MIMCAP,DRAM, ferroelectric tunnel junction (FTJ), FeFET (memory or logic), orRRAM.

Turning now to a more detailed description of aspects of the presentinvention, FIGS. 3-6 depict cross-sectional views of a portion of asemiconductor wafer/structure 300 that includes a substrate 302 afterfabrication operations for forming a ternary oxide film (shown in FIG.6) from an ALD process using M1La-M2Lb-O cycles according to embodimentsof the invention. More specifically, FIG. 3 depicts a cross-sectionalview illustrating two instances of an initial wafer/structure/substrate302 that result from performing initial fabrication operations inaccordance with embodiments of this invention.

As shown in FIG. 3, a substrate 302 (the topmost image) is formed usingknown semiconductor fabrication techniques, and a surface of thesubstrate 302 is exposed to a first precursor M1La to form a first ALDlayer 304 during a first pulse of an ALD cycle as shown in thebottommost image of the substrate 302. In some embodiments of theinvention, the first ALD layer 304 includes the chemisorbed metal 306 ofthe first precursor M1La and its remaining ligands. The first precursorM1La and its remaining ligands can block some or all of theadsorption/reaction sites. In some embodiments of the invention, one ormore adsorption sites 308 remain open on the surface of the substrate302. In some embodiments of the invention, the first pulse only resultsin the deposition of a single layer of the chemisorbed metal 306.

The substrate 302 can be made of any suitable substrate material, suchas, for example, silicon, silicon germanium, silicon carbide (SiC),amorphous doped silicon (e.g., aSi:H), Group III-V compoundsemiconductor, Group II-VI compound semiconductor, orsemiconductor-on-insulator (SOI). Group III-V compound semiconductorsinclude materials having at least one group III element and at least onegroup V element, such as, for example, one or more of aluminum galliumarsenide (AlGaAs), aluminum gallium nitride (AlGaN), aluminum arsenide(AlAs), aluminum indium arsenide (AlIAs), aluminum nitride (AlN),gallium antimonide (GaSb), gallium aluminum antimonide (GaAlSb), galliumarsenide (GaAs), gallium arsenide antimonide (GaAsSb), gallium nitride(GaN), indium antimonide (InSb), indium arsenide (InAs), indium galliumarsenide (InGaAs), indium gallium arsenide phosphide (InGaAsP), indiumgallium nitride (InGaN), indium nitride (InN), indium phosphide (InP)and alloy combinations including at least one of the foregoingmaterials. The alloy combinations can include binary (two elements,e.g., gallium (III) arsenide (GaAs)), ternary (three elements, e.g.,InGaAs) and quaternary (four elements, e.g., aluminum gallium indiumphosphide (AlInGaP)) alloys. Group II-IV compound semiconductors includematerials having at least one group II element and at least one group IVelement, in a similar manner as Group III-V compound semiconductors. Insome embodiments of the invention, the substrate 302 includes a buriedoxide layer (not depicted). The buried oxide layer can be made of anysuitable dielectric material, such as, for example, a silicon oxide. Insome embodiments of the invention, the buried oxide layer is formed to athickness of about 145 nm, although other thicknesses are within thecontemplated scope of the invention.

The first precursor M1La can include a metal (M1) and a ligand (La). Themetal can include any suitable material (even nonmetal semiconductors),such as, for example, Hf, Ta, Zr, Al, La, Si, etc. The ligand caninclude any suitable material, such as, for example, halides, a chloride(Cl₄ or Cl₃), or a metalorganic (trimethyl metalorganics,tetramethylethyl metalorganic, etc., such as Al₂(CH₃)₆).

While not illustrated for ease of discussion, in some embodiments of theinvention, the first pulse (and in fact, any of the pulses, includingall precursor and oxidant pulses) is followed by a non-reactive purgepulse. The purge pulse does not affect the final chemistry, and adetailed discussion of the purge pulses is omitted for simplicity. Thepurge pulses can include, for example, N₂, Ar, He, vacuum, etc., and canbe used to purge off-gasses and unreacted precursor gasses.

FIG. 4 depicts a cross-sectional view illustrating two instances of thesemiconductor structure 300 after processing operations according to oneor more embodiments of the invention. As illustrated in FIG. 4, thesurface of the substrate 302 (the topmost image) is exposed to a secondprecursor M2Lb to fill in any (some, or all) of the one or moreadsorption sites 308 in the first ALD layer 304 during a second pulse ofan ALD cycle (as shown in the bottommost image). In some embodiments ofthe invention, the second precursor M2Lb includes a different material(M2) than the first precursor M1La. In some embodiments of theinvention, the second precursor M2Lb includes a different ligand (Lb)than the first precursor M1La.

In some embodiments of the invention, the different ligands La and Lbcorrespond to distinct halides and metal-organic ligands, includingamines and carbo-hydrates. In some embodiments of the invention, thefirst ligand La and the second ligand Lb are selected from a same classof ligands (e.g., both are halides, metalorganics, etc.). In someembodiments of the invention, the first ligand La is selected from afirst class of ligands (e.g., a halide) and the second ligand Lb isselected from a second class of ligands (e.g., a metalorganic). Forexample, the metal M1 can be hafnium (Hf), the metal M2 can be zirconium(Zr) and the different precursors can include a combination of ZrCl4,HfCl4, TEMAHf, and TDMAHf, TDMAZr, etc., depending on the application.

In some embodiments of the invention, the first ligand La of the firstprecursor M1La reacts with the second ligand Lb of the second precursorM1Lb during the second pulse. In some embodiments of the invention, thereacted ligands La and Lb form an off-gas that is removed from thesemiconductor structure 300. In some embodiments of the invention, whatremains in the first ALD layer 304 after off-gassing are the metals M1and M2 and some residuals (unreacted ligands and reaction byproductssuch as N, Cl, C, H).

In some embodiments of the invention, the first ALD layer 304 includesthe chemisorbed metal 306 of the first precursor M1La, the chemisorbedmetal 402 of the second precursor M2Lb, and any remaining (unreacted)ligands. As discussed previously herein, the first precursor M1La andits remaining ligands can block some or all of the adsorption sites 308during the first pulse. In some embodiments of the invention, the secondpulse immediately follows the first pulse.

By performing the second pulse right after the first pulse (i.e., byexposing the substrate 302 directly to the second precursor M2Lb withoutan oxidant pulse), the M2Lb uptake will be self-limited to the availablereaction sites (e.g., the one or more open adsorption sites 308). Inthis manner, the first ALD layer 304 can be formedsub-stoichiometrically. In some embodiments of the invention, thechemisorbed metal 402 of the second precursor M1Lb reacts with thechemisorbed metal 306 of the first precursor M1La. In other words, thefirst ALD layer 304 can be a sub-oxide having M1-M2 metallic bonds.

As discussed previously herein, the relative sizes of the first ligandLa and the second ligand Lb can be selected to achieve a target M2uptake. In some embodiments of the invention, a relatively small (withrespect to the first ligand La) second ligand Lb is selected to increasethe M2 uptake. Without wishing to be bound by theory, the smaller Lbligands are more easily able to access the one or more open adsorptionsites 308. In some embodiments of the invention, a relatively large(with respect to the first ligand La) second ligand Lb is selected todecrease the M2 uptake. Without wishing to be bound by theory, thelarger Lb ligands have difficulty accessing the one or more openadsorption sites 308.

In some embodiments of the invention, experiments are made for a rangeof possible first and second ligands over a same number of cycles andthe M2 uptake is measured in each case. In some embodiments of theinvention, a list or database of achieved M2 uptake concentrations isgenerated for the various combinations of first and second ligands. Insome embodiments of the invention, the order of the M1 and M2 depositionpulses are swapped. An example list of possible ligands and theresulting M2 uptake for depositing an HfZr ternary oxide is shown inFIG. 2. It is understood, however, that different lists having anynumber of ligand combinations for any arbitrary metals (M1 and M2selections) can be generated using this experimental method. Once aselection of possible first and second ligands are their correspondingM2 uptake concentrations are known, the actual first and second ligandscan be selected to target a specific M2 uptake.

In some embodiments of the invention, the first and/or second ligandscan be swapped out after finishing a partial portion of the total cyclesto further refine the M2 uptake percent. For example, if a firstselection of ligands (L1 and L2) provides 40% M2 uptake and a secondselection of ligands (L3 and L4) provides 20% M2 uptake, then formingthe first half of the film stack using the first selection of ligandsand then finishing the film stack using the second selection of ligandswill result in an M2 uptake of about 30%. Notably, this can be achievedwithout changing the number of cycles or final film thickness.

FIG. 5 depicts a cross-sectional view illustrating two instances of thesemiconductor structure 300 after a processing operation according toone or more embodiments of the invention. As illustrated in FIG. 5, thesurface of the first ALD layer 304 is exposed to an oxidant (denoted“O”) during an oxidant pulse of the ALD cycle (as shown in thebottommost image). In some embodiments of the invention, the oxidant Ocan include, for example, H₂O, N₂O, NO, O₃, O₂, etc. In some embodimentsof the invention, the oxidant pulse results in a single oxidant layer502 forming on a surface of the first ALD layer 304.

FIG. 6 depicts a cross-sectional view illustrating two instances of thesemiconductor structure 300 after a processing operation according toone or more embodiments of the invention. As illustrated in FIG. 6, thesemiconductor structure 300 is exposed to “X” repeated cycles of the ALDpulse (M1La-M2Lb-O) depicted in FIGS. 3-5 to build additional layers 602(as shown in the bottommost image).

In some embodiments of the invention, the layers 602 are built bysequentially exposing the surface of the substrate 302 to: (1) a pulseof the first precursor M1La to form an ALD layer (as described withrespect to FIG. 3); (2) a pulse of the second precursor M2Lb to fill inany (some, or all) of one or more adsorption sites in the ALD layer (asdescribed with respect to FIG. 4); (3) an oxidant pulse (as describedwith respect to FIG. 5); and (4) repeating as needed. The layers 602 canbe formed to any arbitrary thickness by increasing the number “X” of therepeated M1La-M2Lb-O cycles as desired.

FIGS. 7A and 7B depict top-down and cross-sectional views, respectively,of a semiconductor structure 700 after a processing operation accordingto one or more embodiments of the invention. As illustrated in FIG. 7A,the semiconductor structure 700 can define part of a MIM structure(e.g., planar X-point or stacked 3D RRAM). The semiconductor structure700 can include, for example, a metal line 702, an ALD ternary oxide704, and an electrode 706. The metal line 702 and the electrode 706 canbe formed using known processes. In some embodiments of the invention,the ALD ternary oxide 704 is formed according to one or more embodimentsof the invention. In some embodiments of the invention, the ALD ternaryoxide 704 is formed sequentially using M1La-M2Lb-O) cycles. In someembodiments of the invention, the La and Lb ligands are selected toachieve a particular M2 uptake, as discussed previously herein.

The semiconductor structure 700 illustrates one possible application forthe ternary oxides formed using the previously described techniques inaccordance with one or more embodiments. It is understood, however, thatthe previously described techniques can be incorporated in otherprocesses. Advantageously, this ternary oxide ALD technique can replaceor supplement any FEOL or BEOL process whereby oxide films or sub-oxidefilms are needed (e.g., the high-k dielectric film in FETs, theinsulator of a MIMCAP, etc.). In another example, the silicon nitride ina 3D charge-trap flash memory is replaced with an ALD ternary oxide film(e.g., MO-N,C,H,Cl) formed according to one or more embodiments of theinvention.

FIG. 8 depicts a flow diagram 800 illustrating a method for depositing acompound (e.g., a ternary oxide film) according to one or moreembodiments of the invention. As shown at block 802, a first precursoris selected. The first precursor can include a first metal and a firstligand. At block 804, a second precursor is selected. The secondprecursor can include a second metal and a second ligand. The secondmetal is different than the first metal. In some embodiments of theinvention, the second ligand is selected based on the first ligand totarget a second metal uptake, as discussed previously herein.

In some embodiments of the invention, the first metal and the secondmetal include one or more of Hf, Ta, Zr, Al, La, and Si. In someembodiments of the invention, the first ligand and the second ligand areselected from a same class (e.g., both chlorides). In some embodimentsof the invention, the first ligand and the second ligand are selectedfrom a different class (e.g., one chloride and one halide). In someembodiments of the invention, the first ligand includes a halide and thesecond ligand includes a metalorganic. In some embodiments of theinvention, the first ligand includes a metalorganic and the secondligand includes a halide. As shown in FIG. 2, varying the order of theligand classes (e.g., a halide first vs. a metalorganic first) canresult in a change to the M2 uptake. In some embodiments of theinvention, the order of the ligand classes is swapped to further tunethe M2 uptake.

At block 806, a substrate is exposed to the first precursor during afirst pulse of an ALD cycle. In some embodiments of the invention,during the first pulse the first metal of the first precursor chemisorbsonto a surface of the substrate. In some embodiments of the invention,one or more adsorption sites remain open after the first pulse.

At block 808, the substrate is exposed to the second precursor during asecond pulse of the ALD cycle. In some embodiments of the invention, thesecond pulse occurs directly after the first pulse. In some embodimentsof the invention, the second pulse occurs after the first pulse suchthat any intervening pulse is a non-reactive purge pulse (e.g., withoutan intervening oxidant pulse).

In some embodiments of the invention, during the second pulse the secondmetal of the second precursor chemisorbs onto the one or more openadsorption sites which remain open after the first pulse. In someembodiments of the invention, the metal of the second precursorchemisorbs onto a coated surface terminated by the first precursorligands.

In some embodiments of the invention, the first ligand and the secondligand react during the second pulse to form one or more byproducts. Insome embodiments of the invention, at least a portion of the one or morebyproducts are removed via off-gassing.

At block 810, the substrate is exposed to a third precursor during athird pulse of the ALD cycle. In some embodiments of the invention, theternary compound includes a ternary oxide film and the third precursorincludes an oxidant.

In some embodiments of the invention, a precursor partial pressure, gasflow, and pulse time are selected for at least one of the first pulseand the second pulse based on the target second metal uptake. In someembodiments of the invention, these parameters are modified to furthertune the M2 uptake. M2 uptake can vary based on the underlyingchemisorbsion mechanisms (i.e., the ratio of M2 chemisorbsion to opensites versus chemisorbsion to M1 ligands). As the M1La pulse timeincreases, chemisorbsion to open sites decreases (due in part to thefirst precursor taking more and more of the previously open sites). Notethat as the first pulse time trends towards infinite, M2 uptakedecreases to a limit that is based on the physical size of the M1Lacompound).

Moreover, while the formation of a ternary compound (e.g., a ternaryoxide film having a first metal, a second metal, and an oxidant) isdescribed in detail for ease of discussion, it is understood that ALDprocesses in accordance with aspects of the invention can be used toform compounds having any number of elements. In some embodiments of theinvention, new precursors having different metals and/or ligands can bedeposited over the initial film layer(s). In this manner, films havingcompounds with any number of elements can be formed.

FIG. 9 depicts a flow diagram 900 illustrating a method for forming aternary oxide according to one or more embodiments of the invention. Asshown at block 902, a first metal and a second metal are selected forthe ternary oxide. For example, the first metal can be Hf and the secondmetal can be Zr, although other metal selections are within thecontemplated scope of the invention.

At block 904, a target second metal uptake is selected for the ternaryoxide, as discussed previously herein. The target second metal uptakecan vary depending on the application, and can range from 0.5% to 99%.In some embodiments of the invention, the target second metal uptake isless than 15%, less than 10%, less than 5%, less than 3%, less than 2%,or less than 1%.

At block 906, one or more ligand pairs with known second metal uptakesare determined and stored for later selection based on the first metaland the second metal. As discussed previously herein, any number ofligand pairs and associated second metal uptake percentages can beexperimentally determined for any number of first metal/second metalpairs. In this manner, a range of possible ligand pairs with knownsecond metal uptake percentages can be determined for a range ofmetal-metal combinations.

At block 908, a first ligand pair of the one or more ligand pairs isselected, based on the targeted second metal uptake and the known secondmetal uptakes. For example, if the first metal is Hf, the second metalis Zr, and a target Zr uptake is 15%, the first ligand can be Cl₄ andthe second ligand can be TEMA. As shown in FIG. 2, this selectionresults in a Zr uptake of about 15.6%. While this particular example isdeveloped for ease of discussion, other metal and ligand combinations,and targeted second metal uptakes, are possible.

At block 910, a substrate is exposed to an ALD cycle. The ALD cycle caninclude a first precursor pulse, a second precursor pulse, and anoxidant pulse. The first precursor can include the first metal and thefirst ligand and the second precursor can include the second metal andthe second ligand.

In some embodiments of the invention, the method further includesselecting, based on the target second metal uptake and the known secondmetal uptakes, a second ligand pair of the one or more ligand pairs. Thesecond ligand pair can include a third ligand and a fourth ligand. Asdiscussed previously herein, the second ligand pair can be combined withthe first ligand pair to further tune the second metal uptake.

In some embodiments of the invention, the ALD cycle is a first ALD cycleand only a first portion of the ternary oxide is formed using the firstALD cycle. In some embodiments of the invention, a second portion of theternary oxide is formed using a second ALD cycle. In some embodiments ofthe invention, the second ALD cycle includes a third precursor pulse, afourth precursor pulse, and an oxidant pulse. The third precursor caninclude the first metal and the third ligand, and the fourth precursorcan include the second metal and the fourth ligand.

Forming the ternary oxide from two successive ALD cycles havingdifferent ligand pairs offers some advantages over a single ALD cycle.One advantage is that the M2 cation % can change within the ternaryoxide film (i.e., the first portion can have a first uptake, and thesecond portion can have a different uptake). In other words, the ternaryoxide film can have a gradient of M2 concentrations. This process can beexpanded to cover any number of successive ALD cycles, each having adifferent ligand pair selection (but the same first metal and secondmetal). In this manner, the resulting ternary oxide film can have anynumber of layers, each having a different M2 concentration. Thisapproach results in a nanolaminate type structure with layer by layerM1/M2 cation concentration percentages that vary laterally through thefilm (and having any arbitrary gradient), resulting in a filmcomposition that differs considerably from nanolaminates made usingconventional ALD (i.e., where each layer is either M1 or M2, as shown inFIG. 1).

In some embodiments of the invention, the first ligand is selected froma first class of ligands (e.g. a halide, a chloride, a metalorganic,etc.) and the second ligand is selected from a second class of ligandsdifferent than the first class.

In some embodiments of the invention, the ternary oxide includes aferroelectric phase or an anti-ferroelectric phase.

FIG. 10 depicts a flow diagram 1000 illustrating a method for forming anelectronic device according to one or more embodiments of the invention.As shown at block 1002, a bottom layer is formed. In some embodiments ofthe invention, the bottom layer includes a semiconductor material. Insome embodiments of the invention, the semiconductor material includesone or more of Si, Ge, SiGe, aSi:H, and InGaAs. In some embodiments ofthe invention, the bottom layer includes a bottom electrode. In someembodiments of the invention, the bottom electrode includes a metal. Insome embodiments of the invention, the bottom electrode includes ametal-nitride and the metal-sub-oxide film includes HfO_(2-x) orTa₂O_(3-x).

At block 1004, a ternary oxide film is formed over the bottom layer. Theternary oxide film can formed by exposing the bottom layer to an ALDcycle having a first precursor pulse, a second precursor pulse, and anoxidant pulse. The first precursor can include a first metal and a firstligand and the second precursor can include a second metal and a secondligand. The second ligand can be selected based on the first ligand totarget a second metal uptake, as discussed previously herein.

In some embodiments of the invention, the ternary oxide film includes athickness of less than about 2 nm and a second metal concentration ofless than 15 percent. In some embodiments of the invention, the secondmetal is distributed throughout the ternary oxide film. In other words,the second metal is not confined to dedicated layers as is the case forconventional ALD (see FIG. 1).

At block 1006, a top electrode is formed over the bottom layer. In someembodiments of the invention, the ternary oxide film is an active areaof a resistive random-access memory (RRAM). In some embodiments of theinvention, the ternary oxide film is a gate dielectric layer of afloating gate flash memory. In some embodiments of the invention, theternary oxide film includes one or more metal-metal bonds and/or one ormore metal-nitride-metal bonds. In some embodiments of the invention,the ternary oxide film includes sub-oxide bonds coupled with organic andhalide byproducts (e.g., C, Cl, NH₃Cl, etc.). The presence of thesesub-oxide bonds coupled with organic and halide byproducts can serve asa fingerprint when determining whether a particular ternary oxide filmwas formed according to one or more embodiments of the presentinvention.

The methods described herein can be used in the fabrication of IC chips.The resulting integrated circuit chips can be distributed by thefabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

Various embodiments of the present invention are described herein withreference to the related drawings. Alternative embodiments can bedevised without departing from the scope of this invention. Althoughvarious connections and positional relationships (e.g., over, below,adjacent, etc.) are set forth between elements in the followingdescription and in the drawings, persons skilled in the art willrecognize that many of the positional relationships described herein areorientation-independent when the described functionality is maintainedeven though the orientation is changed. These connections and/orpositional relationships, unless specified otherwise, can be direct orindirect, and the present invention is not intended to be limiting inthis respect. Similarly, the term “coupled” and variations thereofdescribes having a communications path between two elements and does notimply a direct connection between the elements with no interveningelements/connections between them. All of these variations areconsidered a part of the specification. Accordingly, a coupling ofentities can refer to either a direct or an indirect coupling, and apositional relationship between entities can be a direct or indirectpositional relationship. As an example of an indirect positionalrelationship, references in the present description to forming layer “A”over layer “B” include situations in which one or more intermediatelayers (e.g., layer “C”) is between layer “A” and layer “B” as long asthe relevant characteristics and functionalities of layer “A” and layer“B” are not substantially changed by the intermediate layer(s).

The following definitions and abbreviations are to be used for theinterpretation of the claims and the specification. As used herein, theterms “comprises,” “comprising,” “includes,” “including,” “has,”“having,” “contains” or “containing,” or any other variation thereof,are intended to cover a non-exclusive inclusion. For example, acomposition, a mixture, process, method, article, or apparatus thatcomprises a list of elements is not necessarily limited to only thoseelements but can include other elements not expressly listed or inherentto such composition, mixture, process, method, article, or apparatus.

Additionally, the term “exemplary” is used herein to mean “serving as anexample, instance or illustration.” Any embodiment or design describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments or designs. The terms “at least one”and “one or more” are understood to include any integer number greaterthan or equal to one, i.e. one, two, three, four, etc. The terms “aplurality” are understood to include any integer number greater than orequal to two, i.e. two, three, four, five, etc. The term “connection”can include an indirect “connection” and a direct “connection.”

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” etc., indicate that the embodiment describedcan include a particular feature, structure, or characteristic, butevery embodiment may or may not include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

For purposes of the description hereinafter, the terms “upper,” “lower,”“right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” andderivatives thereof shall relate to the described structures andmethods, as oriented in the drawing figures. The terms “overlying,”“atop,” “on top,” “positioned on” or “positioned atop” mean that a firstelement, such as a first structure, is present on a second element, suchas a second structure, wherein intervening elements such as an interfacestructure can be present between the first element and the secondelement. The term “direct contact” means that a first element, such as afirst structure, and a second element, such as a second structure, areconnected without any intermediary conducting, insulating orsemiconductor layers at the interface of the two elements.

Spatially relative terms, e.g., “beneath,” “below,” “lower,” “above,”“upper,” and the like, can be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the term “below” can encompass both an orientation ofabove and below. The device can be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

The terms “about,” “substantially,” “approximately,” and variationsthereof, are intended to include the degree of error associated withmeasurement of the particular quantity based upon the equipmentavailable at the time of filing the application. For example, “about”can include a range of +8% or 5%, or 2% of a given value.

The term “conformal” (e.g., a conformal layer) means that the thicknessof the layer is substantially the same on all surfaces, or that thethickness variation is less than 15% of the nominal thickness of thelayer.

The terms “epitaxial growth and/or deposition” and “epitaxially formedand/or grown” mean the growth of a semiconductor material (crystallinematerial) on a deposition surface of another semiconductor material(crystalline material), in which the semiconductor material being grown(crystalline overlayer) has substantially the same crystallinecharacteristics as the semiconductor material of the deposition surface(seed material). In an epitaxial deposition process, the chemicalreactants provided by the source gases can be controlled and the systemparameters can be set so that the depositing atoms arrive at thedeposition surface of the semiconductor substrate with sufficient energyto move about on the surface such that the depositing atoms orientthemselves to the crystal arrangement of the atoms of the depositionsurface. An epitaxially grown semiconductor material can havesubstantially the same crystalline characteristics as the depositionsurface on which the epitaxially grown material is formed. For example,an epitaxially grown semiconductor material deposited on a (100)orientated crystalline surface can take on a (100) orientation. In someembodiments of the invention, epitaxial growth and/or depositionprocesses can be selective to forming on semiconductor surface, andcannot deposit material on exposed surfaces, such as silicon dioxide orsilicon nitride surfaces.

As previously noted herein, for the sake of brevity, conventionaltechniques related to semiconductor device and integrated circuit (IC)fabrication may or may not be described in detail herein. By way ofbackground, however, a more general description of the semiconductordevice fabrication processes that can be utilized in implementing one ormore embodiments of the present invention will now be provided. Althoughspecific fabrication operations used in implementing one or moreembodiments of the present invention can be individually known, thedescribed combination of operations and/or resulting structures of thepresent invention are unique. Thus, the unique combination of theoperations described in connection with the fabrication of asemiconductor device according to the present invention utilize avariety of individually known physical and chemical processes performedon a semiconductor (e.g., silicon) substrate, some of which aredescribed in the immediately following paragraphs.

In general, the various processes used to form a micro-chip that will bepackaged into an IC fall into four general categories, namely, filmdeposition, removal/etching, semiconductor doping andpatterning/lithography. Deposition is any process that grows, coats, orotherwise transfers a material onto the wafer. Available technologiesinclude physical vapor deposition (PVD), chemical vapor deposition(CVD), electrochemical deposition (ECD), molecular beam epitaxy (MBE)and more recently, atomic layer deposition (ALD) among others.Removal/etching is any process that removes material from the wafer.Examples include etch processes (either wet or dry), chemical-mechanicalplanarization (CMP), and the like. Reactive ion etching (RIE), forexample, is a type of dry etching that uses chemically reactive plasmato remove a material, such as a masked pattern of semiconductormaterial, by exposing the material to a bombardment of ions thatdislodge portions of the material from the exposed surface. The plasmais typically generated under low pressure (vacuum) by an electromagneticfield. Semiconductor doping is the modification of electrical propertiesby doping, for example, transistor sources and drains, generally bydiffusion and/or by ion implantation. These doping processes arefollowed by furnace annealing or by rapid thermal annealing (RTA).Annealing serves to activate the implanted dopants. Films of bothconductors (e.g., poly-silicon, aluminum, copper, etc.) and insulators(e.g., various forms of silicon dioxide, silicon nitride, etc.) are usedto connect and isolate transistors and their components. Selectivedoping of various regions of the semiconductor substrate allows theconductivity of the substrate to be changed with the application ofvoltage. By creating structures of these various components, millions oftransistors can be built and wired together to form the complexcircuitry of a modern microelectronic device. Semiconductor lithographyis the formation of three-dimensional relief images or patterns on thesemiconductor substrate for subsequent transfer of the pattern to thesubstrate. In semiconductor lithography, the patterns are formed by alight sensitive polymer called a photo-resist. To build the complexstructures that make up a transistor and the many wires that connect themillions of transistors of a circuit, lithography and etch patterntransfer steps are repeated multiple times. Each pattern being printedon the wafer is aligned to the previously formed patterns and slowly theconductors, insulators and selectively doped regions are built up toform the final device.

The flowchart and block diagrams in the Figures illustrate possibleimplementations of fabrication and/or operation methods according tovarious embodiments of the present invention. Variousfunctions/operations of the method are represented in the flow diagramby blocks. In some alternative implementations, the functions noted inthe blocks can occur out of the order noted in the Figures. For example,two blocks shown in succession can, in fact, be executed substantiallyconcurrently, or the blocks can sometimes be executed in the reverseorder, depending upon the functionality involved.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments described. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdescribed herein.

What is claimed is:
 1. A method of depositing a compound, the methodcomprising: selecting a first precursor comprising a first metal and afirst ligand; selecting a second precursor comprising a second metal anda second ligand, the second metal different than the first metal, thesecond ligand selected based on the first ligand to target a secondmetal uptake, wherein the target second metal uptake comprises a finalsecond metal concentration in the compound; exposing a substrate to thefirst precursor during a first pulse of an atomic layer deposition (ALD)cycle; exposing the substrate to the second precursor during a secondpulse of the ALD cycle, the second pulse occurring after the firstpulse; and exposing the substrate to a third precursor during a thirdpulse of the ALD cycle.
 2. The method of claim 1 further comprisingselecting a precursor partial pressure, gas flow, and pulse time for atleast one of the first pulse and the second pulse based on the targetsecond metal uptake.
 3. The method of claim 1, wherein the compoundcomprises a ternary oxide and the third precursor is an oxidant.
 4. Themethod of claim 1, wherein during the first pulse the first metal of thefirst precursor adsorbs onto a surface of the substrate.
 5. The methodof claim 4, wherein one or more adsorption sites remain open after thefirst pulse; and wherein during the second pulse the second metal of thesecond precursor chemisorbs onto the one or more open adsorption sites.6. The method of claim 1, wherein the first ligand and the second ligandreact during the second pulse to form one or more byproducts; andwherein at least a portion of the one or more byproducts are removed viaoff-gassing.
 7. The method of claim 1, wherein the second pulse occursdirectly after the first pulse without an intervening pulse.
 8. Themethod of claim 1, wherein the second pulse occurs after the first pulsesuch that any intervening pulse is a non-reactive purge pulse.
 9. Themethod of claim 1, wherein the first metal comprises one or more of Hf,Ta, Zr, Al, La, and Si, the second metal comprises one or more of Hf,Ta, Zr, Al, La, and Si, the first ligand comprises a halide, and thesecond ligand comprises a metalorganic.
 10. The method of claim 1,wherein the first metal comprises one or more of Hf, Ta, Zr, Al, La, andSi, the second metal comprises one or more of Hf, Ta, Zr, Al, La, andSi, the first ligand comprises a metalorganic, and the second ligandcomprises a halide.
 11. An electronic device comprising: a bottom layer;a top electrode; and a ternary oxide film between the bottom layer andthe top electrode, the ternary oxide film formed by exposing the bottomlayer to an atomic layer deposition (ALD) cycle, the ALD cyclecomprising a first precursor pulse, a second precursor pulse, and anoxidant pulse, wherein the first precursor pulse comprises a first metaland a first ligand and the second precursor pulse comprises a secondmetal and a second ligand; wherein the ternary oxide film comprises athickness of less than about 2 nm and a second metal concentration ofless than 15 percent, and wherein the second metal is distributedthroughout the ternary oxide film.
 12. The device of claim 11, whereinthe second metal concentration is less than about 6 percent.
 13. Thedevice of claim 11, wherein the electronic device comprises afield-effect transistor.
 14. The device of claim 11, wherein the ternaryoxide film comprises an active area of at least one of a ferroelectricdevice and a resistive random-access memory (RRAM) device.
 15. Ametal-insulator-metal device comprising: a bottom electrode comprising afirst metal; a top electrode comprising a second metal; and a ternaryoxide film between the bottom electrode and the top electrode, theternary oxide film formed by exposing the bottom electrode to an atomiclayer deposition (ALD) cycle, the ALD cycle comprising a first precursorpulse, a second precursor pulse, and an oxidant pulse, wherein the firstprecursor pulse comprises a third metal and a first ligand and thesecond precursor pulse comprises a fourth metal and a second ligand;wherein the ternary oxide film comprises a thickness of less than about2 nm and a second metal concentration of less than 15 percent, andwherein the second metal is distributed throughout the ternary oxidefilm.
 16. The device of claim 15, wherein the ternary oxide filmcomprises organic and halide byproducts.